/* ymodem for RTD Serial Recovery (rtdsr)
 *
 * copyright (c) 2011 Pete B. <xtreamerdev@gmail.com>
 *
 * based on ymodem.c for bootldr, copyright (c) 2001 John G Dorsey
 * baded on ymodem.c for reimage, copyright (c) 2009 Rich M Legrand
 * crc16 function from PIC CRC16, by Ashley Roll & Scott Dattalo
 * crc32 function from crc32.c by Craig Bruce
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 *
 */

/*
 * These Ymodem calls are aimed at embedded software and tailored to
 * work against Microsoft's HyperTerminal. Some of the Ymodem protocol
*  operations have been voluntarily left out.
 *
 * To be able to use these functions, you must provide:
 * o int _getchar(int timeout): A serial getchar() call, with a
 *   timeout expressed in seconds. Negative means infinite timeout.
 *   should return the read character, as an int, or negative on
 *   error/timeout.
 * o void _putchar(int c): A serial putchar() call
 * o printf(), thought all the printfs can be removed if needed.
 */

#include "util.h"
#include "printf.h"
#include "ymodem.h"

#ifdef WITH_CRC32
/* http://csbruce.com/~csbruce/software/crc32.c */
static unsigned long crc32(const unsigned char* buf, unsigned long count)
{
	unsigned long crc = 0xFFFFFFFF;
	unsigned long i;

	/* This static table adds 1K */
	static const unsigned long crc_table[256] = {
		0x00000000,0x77073096,0xEE0E612C,0x990951BA,0x076DC419,0x706AF48F,0xE963A535,
		0x9E6495A3,0x0EDB8832,0x79DCB8A4,0xE0D5E91E,0x97D2D988,0x09B64C2B,0x7EB17CBD,
		0xE7B82D07,0x90BF1D91,0x1DB71064,0x6AB020F2,0xF3B97148,0x84BE41DE,0x1ADAD47D,
		0x6DDDE4EB,0xF4D4B551,0x83D385C7,0x136C9856,0x646BA8C0,0xFD62F97A,0x8A65C9EC,
		0x14015C4F,0x63066CD9,0xFA0F3D63,0x8D080DF5,0x3B6E20C8,0x4C69105E,0xD56041E4,
		0xA2677172,0x3C03E4D1,0x4B04D447,0xD20D85FD,0xA50AB56B,0x35B5A8FA,0x42B2986C,
		0xDBBBC9D6,0xACBCF940,0x32D86CE3,0x45DF5C75,0xDCD60DCF,0xABD13D59,0x26D930AC,
		0x51DE003A,0xC8D75180,0xBFD06116,0x21B4F4B5,0x56B3C423,0xCFBA9599,0xB8BDA50F,
		0x2802B89E,0x5F058808,0xC60CD9B2,0xB10BE924,0x2F6F7C87,0x58684C11,0xC1611DAB,
		0xB6662D3D,0x76DC4190,0x01DB7106,0x98D220BC,0xEFD5102A,0x71B18589,0x06B6B51F,
		0x9FBFE4A5,0xE8B8D433,0x7807C9A2,0x0F00F934,0x9609A88E,0xE10E9818,0x7F6A0DBB,
		0x086D3D2D,0x91646C97,0xE6635C01,0x6B6B51F4,0x1C6C6162,0x856530D8,0xF262004E,
		0x6C0695ED,0x1B01A57B,0x8208F4C1,0xF50FC457,0x65B0D9C6,0x12B7E950,0x8BBEB8EA,
		0xFCB9887C,0x62DD1DDF,0x15DA2D49,0x8CD37CF3,0xFBD44C65,0x4DB26158,0x3AB551CE,
		0xA3BC0074,0xD4BB30E2,0x4ADFA541,0x3DD895D7,0xA4D1C46D,0xD3D6F4FB,0x4369E96A,
		0x346ED9FC,0xAD678846,0xDA60B8D0,0x44042D73,0x33031DE5,0xAA0A4C5F,0xDD0D7CC9,
		0x5005713C,0x270241AA,0xBE0B1010,0xC90C2086,0x5768B525,0x206F85B3,0xB966D409,
		0xCE61E49F,0x5EDEF90E,0x29D9C998,0xB0D09822,0xC7D7A8B4,0x59B33D17,0x2EB40D81,
		0xB7BD5C3B,0xC0BA6CAD,0xEDB88320,0x9ABFB3B6,0x03B6E20C,0x74B1D29A,0xEAD54739,
		0x9DD277AF,0x04DB2615,0x73DC1683,0xE3630B12,0x94643B84,0x0D6D6A3E,0x7A6A5AA8,
		0xE40ECF0B,0x9309FF9D,0x0A00AE27,0x7D079EB1,0xF00F9344,0x8708A3D2,0x1E01F268,
		0x6906C2FE,0xF762575D,0x806567CB,0x196C3671,0x6E6B06E7,0xFED41B76,0x89D32BE0,
		0x10DA7A5A,0x67DD4ACC,0xF9B9DF6F,0x8EBEEFF9,0x17B7BE43,0x60B08ED5,0xD6D6A3E8,
		0xA1D1937E,0x38D8C2C4,0x4FDFF252,0xD1BB67F1,0xA6BC5767,0x3FB506DD,0x48B2364B,
		0xD80D2BDA,0xAF0A1B4C,0x36034AF6,0x41047A60,0xDF60EFC3,0xA867DF55,0x316E8EEF,
		0x4669BE79,0xCB61B38C,0xBC66831A,0x256FD2A0,0x5268E236,0xCC0C7795,0xBB0B4703,
		0x220216B9,0x5505262F,0xC5BA3BBE,0xB2BD0B28,0x2BB45A92,0x5CB36A04,0xC2D7FFA7,
		0xB5D0CF31,0x2CD99E8B,0x5BDEAE1D,0x9B64C2B0,0xEC63F226,0x756AA39C,0x026D930A,
		0x9C0906A9,0xEB0E363F,0x72076785,0x05005713,0x95BF4A82,0xE2B87A14,0x7BB12BAE,
		0x0CB61B38,0x92D28E9B,0xE5D5BE0D,0x7CDCEFB7,0x0BDBDF21,0x86D3D2D4,0xF1D4E242,
		0x68DDB3F8,0x1FDA836E,0x81BE16CD,0xF6B9265B,0x6FB077E1,0x18B74777,0x88085AE6,
		0xFF0F6A70,0x66063BCA,0x11010B5C,0x8F659EFF,0xF862AE69,0x616BFFD3,0x166CCF45,
		0xA00AE278,0xD70DD2EE,0x4E048354,0x3903B3C2,0xA7672661,0xD06016F7,0x4969474D,
		0x3E6E77DB,0xAED16A4A,0xD9D65ADC,0x40DF0B66,0x37D83BF0,0xA9BCAE53,0xDEBB9EC5,
		0x47B2CF7F,0x30B5FFE9,0xBDBDF21C,0xCABAC28A,0x53B39330,0x24B4A3A6,0xBAD03605,
		0xCDD70693,0x54DE5729,0x23D967BF,0xB3667A2E,0xC4614AB8,0x5D681B02,0x2A6F2B94,
		0xB40BBE37,0xC30C8EA1,0x5A05DF1B,0x2D02EF8D
	};

	for (i=0; i<count; i++) {
		crc = (crc >> 8) ^ crc_table[(crc ^ buf[i]) & 0xFF];
	}
	return(crc ^ 0xFFFFFFFF);
}
#endif

/* http://www.ccsinfo.com/forum/viewtopic.php?t=24977 */
static unsigned short crc16(const unsigned char *buf, unsigned long count)
{
	unsigned short crc = 0;
	int i;

	while(count--) {
		crc = crc ^ *buf++ << 8;

		for (i=0; i<8; i++) {
			if (crc & 0x8000) {
				crc = crc << 1 ^ 0x1021;
			} else {
				crc = crc << 1;
			}
		}
	}
	return crc;
}

static const char *u32_to_str(unsigned int val)
{
	/* Maximum number of decimal digits in u32 is 10 */
	static char num_str[11];
	int  pos = 10;
	num_str[10] = 0;

	if (val == 0) {
		/* If already zero then just return zero */
		return "0";
	}

	while ((val != 0) && (pos > 0)) {
		num_str[--pos] = (val % 10) + '0';
		val /= 10;
	}

	return &num_str[pos];
}

static unsigned long str_to_u32(char* str)
{
	const char *s = str;
	unsigned long acc;
	int c;

	/* strip leading spaces if any */
	do {
		c = *s++;
	} while (c == ' ');

	for (acc = 0; (c >= '0') && (c <= '9'); c = *s++) {
		c -= '0';
		acc *= 10;
		acc += c;
	}
	return acc;
}

/* Returns 0 on success, 1 on corrupt packet, -1 on error (timeout): */
static int receive_packet(char *data, int *length)
{
	int i, c;
	unsigned int packet_size;

	*length = 0;

	c = _getchar(PACKET_TIMEOUT);
	if (c < 0) {
		return -1;
	}

	switch(c) {
	case SOH:
		packet_size = PACKET_SIZE;
		break;
	case STX:
		packet_size = PACKET_1K_SIZE;
		break;
	case EOT:
		return 0;
	case CAN:
		c = _getchar(PACKET_TIMEOUT);
		if (c == CAN) {
			*length = -1;
			return 0;
		}
	default:
		/* This case could be the result of corruption on the first octet
		* of the packet, but it's more likely that it's the user banging
		* on the terminal trying to abort a transfer. Technically, the
		* former case deserves a NAK, but for now we'll just treat this
		* as an abort case.
		*/
		*length = -1;
		return 0;
	}

	*data = (char)c;

	for(i = 1; i < (packet_size + PACKET_OVERHEAD); ++i) {
		c = _getchar(PACKET_TIMEOUT);
		if (c < 0) {
			return -1;
		}
		data[i] = (char)c;
	}

	/* Just a sanity check on the sequence number/complement value.
	 * Caller should check for in-order arrival.
	 */
	if (data[PACKET_SEQNO_INDEX] != ((data[PACKET_SEQNO_COMP_INDEX] ^ 0xff) & 0xff)) {
		return 1;
	}

	if (crc16(data + PACKET_HEADER, packet_size + PACKET_TRAILER) != 0) {
		return 1;
	}
	*length = packet_size;

	return 0;
}

/* Returns the length of the file received, or 0 on error: */
unsigned long ymodem_receive(unsigned char *buf, unsigned long length)
{
	unsigned char packet_data[PACKET_1K_SIZE + PACKET_OVERHEAD];
	int packet_length, i, file_done, session_done, crc_tries, crc_nak;
	unsigned int packets_received, errors, first_try = 1;
	char file_name[FILE_NAME_LENGTH], file_size[FILE_SIZE_LENGTH], *file_ptr;
	unsigned char *buf_ptr;
	unsigned long size = 0;

	printf("Ymodem rcv:\n");
	file_name[0] = 0;

	for (session_done = 0, errors = 0; ; ) {
		crc_tries = crc_nak = 1;
		if (!first_try) {
			_putchar(CRC);
		}
		first_try = 0;
		for (packets_received = 0, file_done = 0, buf_ptr = buf; ; ) {
			switch (receive_packet(packet_data, &packet_length)) {

			case 0:
				errors = 0;
				switch (packet_length) {
					case -1:  /* abort */
						_putchar(ACK);
						return 0;
					case 0:   /* end of transmission */
						_putchar(ACK);
						/* Should add some sort of sanity check on the number of
						 * packets received and the advertised file length.
						 */
						file_done = 1;
						break;
					default:  /* normal packet */
					if ((packet_data[PACKET_SEQNO_INDEX] & 0xff) != (packets_received & 0xff)) {
						_putchar(NAK);
					} else {
						if (packets_received == 0) {
							/* The spec suggests that the whole data section should
							 * be zeroed, but I don't think all senders do this. If
							 * we have a NULL filename and the first few digits of
							 * the file length are zero, we'll call it empty.
							 */
							for (i = PACKET_HEADER; i < PACKET_HEADER + 4; i++) {
								if (packet_data[i] != 0) {
									break;
								}
							}
							if (i < PACKET_HEADER + 4) {  /* filename packet has data */
								for (file_ptr = packet_data + PACKET_HEADER, i = 0; *file_ptr && i < FILE_NAME_LENGTH; ) {
									file_name[i++] = *file_ptr++;
								}
								file_name[i++] = '\0';
								for (++file_ptr, i = 0; *file_ptr != ' ' && i < FILE_SIZE_LENGTH; ) {
									file_size[i++] = *file_ptr++;
								}
								file_size[i++] = '\0';
								size = str_to_u32(file_size);
								if (size > length) {
									_putchar(CAN);
									_putchar(CAN);
									_sleep(1);
									printf("\nrcv buffer too small (0x%08x vs 0x%08x)\n", length, size);
									return 0;
								}
								_putchar(ACK);
								_putchar(crc_nak ? CRC : NAK);
								crc_nak = 0;
							} else {  /* filename packet is empty; end session */
								_putchar(ACK);
								file_done = 1;
								session_done = 1;
								break;
							}
						} else {
							/* This shouldn't happen, but we check anyway in case the
							 * sender lied in its filename packet:
							 */
							if ((buf_ptr + packet_length) - buf > length) {
								_putchar(CAN);
								_putchar(CAN);
								_sleep(1);
								printf("\nbuffer overflow: %d\n", length);
								return 0;
							}
							for (i=0; i<packet_length; i++) {
								buf_ptr[i] = packet_data[PACKET_HEADER+i];
							}
							buf_ptr += packet_length;
							_putchar(ACK);
						}
						++packets_received;
					}  /* sequence number ok */
				}
				break;

			default:
				if (packets_received != 0) {
					if (++errors >= MAX_ERRORS) {
						_putchar(CAN);
						_putchar(CAN);
						_sleep(1);
						printf("\ntoo many errors - aborted.\n");
						return 0;
					}
				}
				_putchar(CRC);
			}
			if (file_done) {
				break;
			}
		}  /* receive packets */

		if (session_done)
			break;

	}  /* receive files */

	printf("\n");
	if (size > 0) {
		printf("read:%s\n", file_name);
#ifdef WITH_CRC32
		printf("crc32:0x%08x, len:0x%08x\n", crc32(buf, size), size);
#else
		printf("len:0x%08x\n", size);
#endif
	}
	return size;
}

static void send_packet(unsigned char *data, int block_no)
{
	int count, crc, packet_size;

	/* We use a short packet for block 0 - all others are 1K */
	if (block_no == 0) {
		packet_size = PACKET_SIZE;
	} else {
		packet_size = PACKET_1K_SIZE;
	}
	crc = crc16(data, packet_size);
	/* 128 byte packets use SOH, 1K use STX */
	_putchar((block_no==0)?SOH:STX);
	_putchar(block_no & 0xFF);
	_putchar(~block_no & 0xFF);

	for (count=0; count<packet_size; count++) {
		_putchar(data[count]);
	}
	_putchar((crc >> 8) & 0xFF);
	_putchar(crc & 0xFF);
}

/* Send block 0 (the filename block). filename might be truncated to fit. */
static void send_packet0(char* filename, unsigned long size)
{
	unsigned long count = 0;
	unsigned char block[PACKET_SIZE];
	const char* num;

	if (filename) {
		while (*filename && (count < PACKET_SIZE-FILE_SIZE_LENGTH-2)) {
			block[count++] = *filename++;
		}
		block[count++] = 0;

		num = u32_to_str(size);
		while(*num) {
			block[count++] = *num++;
		}
	}

	while (count < PACKET_SIZE) {
		block[count++] = 0;
	}

	send_packet(block, 0);
}


static void send_data_packets(unsigned char* data, unsigned long size)
{
	int blockno = 1;
	unsigned long send_size;
	int ch;

	while (size > 0) {
		if (size > PACKET_1K_SIZE) {
			send_size = PACKET_1K_SIZE;
		} else {
			send_size = size;
		}

		send_packet(data, blockno);
		ch = _getchar(PACKET_TIMEOUT);
		if (ch == ACK) {
			blockno++;
			data += send_size;
			size -= send_size;
		} else {
			if((ch == CAN) || (ch == -1)) {
				return;
			}
		}
	}

	do {
		_putchar(EOT);
		ch = _getchar(PACKET_TIMEOUT);
	} while((ch != ACK) && (ch != -1));

	/* Send last data packet */
	if (ch == ACK) {
		ch = _getchar(PACKET_TIMEOUT);
		if (ch == CRC) {
			do {
				send_packet0(0, 0);
				ch = _getchar(PACKET_TIMEOUT);
			} while((ch != ACK) && (ch != -1));
		}
	}
}

unsigned long ymodem_send(unsigned char* buf, unsigned long size, char* filename)
{
	int ch, crc_nak = 1;

	printf("Ymodem send:\n");

	/* Flush the RX FIFO, after a cool off delay */
	_sleep(1);
	while (serial_read() >= 0);

	/* Not in the specs, just for balance */
	do {
		_putchar(CRC);
		ch = _getchar(1);
	} while (ch < 0);

	if (ch == CRC) {
		do {
			send_packet0(filename, size);
			/* When the receiving program receives this block and successfully
			 * opened the output file, it shall acknowledge this block with an ACK
			 * character and then proceed with a normal XMODEM file transfer
			 * beginning with a "C" or NAK tranmsitted by the receiver.
			 */
			ch = _getchar(PACKET_TIMEOUT);

			if (ch == ACK) {
				ch = _getchar(PACKET_TIMEOUT);
				if (ch == CRC) {
					send_data_packets(buf, size);
					printf("\nsent:%s\n", filename);
#ifdef WITH_CRC32
					printf("crc32:0x%08x, len:0x%08x\n", crc32(buf, size), size);
#else
					printf("len:0x%08x\n", size);
#endif
					return size;
				}
			} else if ((ch == CRC) && (crc_nak)) {
				crc_nak = 0;
				continue;
			} else if ((ch != NAK) || (crc_nak)) {
				break;
			}
		} while(1);
	}
	_putchar(CAN);
	_putchar(CAN);
	_sleep(1);
	printf("\naborted.\n");
	return 0;
}
